1. Field of the Invention
The invention relates to an improved feeder channel for distribution of fluid and particles for a well fluid filter separator.
The invention relates to an improved feeder channel for the distribution of well fluid and particles which is fed into a filter separator machine used for separation of undesired particles from a well fluid used in petroleum industry. The separated particles may include cuttings, rock particles, metal particles, additive particles and chemicals. The well fluid may be a water-based (WBM) or an oil based (OBM) drilling fluid if filtering shall be conducted during drilling, or a so-called completion fluid if one intends to circulate under conditions other than drilling.
2. Description of Background Art
Each provider of filter separator machines (shale shakers) has developed their own design for feeder channels. The efficiency and practical usefulness of the fluid and particle distribution on the filter is varied. They do not fully utilize the potentially available filtration area, movement pattern (vibration) and transport length for particles on the filters, or the through flow of well fluids at the same. This potentially incurs reduced quality of the primary cleaning and hence increased consumption of such filters, well fluid and wear on all equipment in contact with the heterogeneous fluid in connection with the particle variations.
WO2009/111730 concerns a fluid distribution apparatus configured to receive a drilling material and direct the drilling material onto a separatory surface; and a damper coupled to the housing and configured to distribute a flow of the drilling material onto the separatory surface.
WO03/028907 describes a vibratory separator and a screen assembly. In the drilling of a borehole in the construction of an oil or gas well, a drill bit is arranged on the end of a drill string and is rotated to bore the borehole. A drilling fluid known as “drilling mud” is pumped through the drill string to the drill bit to lubricate the drill bit. The drilling mud is also used to carry the cuttings produced by the drill bit and other solids to the surface through an annulus formed between the drill string and the borehole. The drilling mud contains expensive synthetic oil-based lubricants and it is normal therefore to recover and re-use the used drilling mud, but this requires the solids to be removed from the drilling mud.
U.S. Pat. No. 4,940,535 relates to an apparatus which distributes the flow of solids to two or more solid separation devices. The apparatus comprises a plenum, such as a horizontally disposed elongated chamber, that is positioned above inlet zones of the solid separation devices. The plenum includes an inlet for communication with a source of the flow of solids and liquid, such as from a drilling well, and also includes lower outlets positioned adjacent the solids separation device's inlet zones. Valves are positioned across these lower outlets for regulating the quantity of solids and liquid that flow to each solid separation device. A variable distribution device, such as a movable or tiltable plate, is connected within the plenum adjacent the solids and liquid inlet for regulating the proportion of solids directed to each solid separation device.
U.S. Pat. No. 5,593,582 describes a shale shaker having two feeds, two screens, two mud outlets and a removable tray between the screens is disclosed. Each screen receives one feed and produces one outlet of cuttings and another outlet for separated mud for either bypass or direct feed to the mud tank or the other screen. The removable tray or trays facilitate the two screens acting in cascade. Valves are provided to control the overall flow rate to the shaker and to the lower level screen.
WO9608301 describes a vibratory screen filter apparatus. In the vibratory screen filter apparatus a plurality of vibratory screening units are provided. Each unit has its own filter screen and vibrating means for vibrating the screen, and receives mixture to the process from a common inlet reservoir which includes means for varying the relative rates of supply of mixture to the screens of the screening units. Sensor means detects the amount of mixture on each screen, and the output of the sensor means is used by control means which controls the amount of mixture deposited on each unit, and can selectively activate or de-activate units to cope with changes in the required rate at which the apparatus is to process a mixture of drilling mud and cuttings.
WO02/40186 discloses a shale shaker for separating material, the shale shaker comprising a basket for supporting a screen assembly, a collection receptacle, and a vibratory mechanism for vibrating the basket, the basket comprising two side walls, an end wall and an opening in the bottom of the basket, the basket having means to support screen assemblies for substantially covering the opening characterized in that the basket further comprises separating means in or on any of the walls for separating material. Preferably, the shale shaker further comprises directing means for directing separated material therefrom into said collection receptacle.
Explanation:
                100% coverage ratio (DG) provides continuous loss of fluid on the top filter.        90% DG provides a risk of loss.        75% DG by even distribution front does not provide loss. Table B: shows the cost per machine filter per drilled meter of formation of sections 24″, 17.5″, 12.25″, and 8.5″.        
The numerical values are from the Norwegian Petroleum Directorate's website for the Norwegian sector for the period 1999-2008 and is based on well specified length. Based on this, the average consumption and the costs are estimated. This is defined as historical data.
An essential problem with the feeder channels in the background art is that they lead fluid and particle flow ahead on the filters in the filter separator machines movement and transport direction—see FIGS. 7A-11. This incurs in a reduced transport path in distance and time from the landing point on the filter to the outlet on the end of the same.
Common to FB & HB, Another essential problem is the lack of utilization of available filtration area of the inner portion of the filter, which is located under and behind the landing point of liquid and particles—see FIGS. 5-8B. This, in practice, provides reduced receiving capacity for liquid and particles at the same filter quality.
This is common for feeder box and header box devices. A third essential problem with the functional design of the feeder channel is that the feeding out section and the degree of cover distribution of fluid particles reflects how the supply to the feeder channel is oriented in its direction and angle.                A vertical or a perpendicular flow provides one type of flow distribution on the filter, see FIGS. 9A and 9B, the arrow indicates the direction of main flow.        An oblique flow from the left, versus right, provides other flow patterns for the same filter, see FIGS. 10 and 11. The arrow indicates the direction the main flow.        
A fourth, substantial problem is related to the HSE (Health and Environment Safety) by personnel exposed to chemical composition of the drilling fluid (risk of chemical pneumonia, etc.) through increased handling of the increasing wear on the primary filter as reduced filter area leads to the use of coarse top filter (scalping screen). Coarser top filter lets through a significant amount of particles (volume & weight), incurring increased wear on the main filter. FIG. 12, Table A illustrates an approximate coverage on the top deck VS filter quality.
A fifth essential problem is economic related in that a high consumption of filter screens during the drilling of a well—please see FIG. 13, Table B, as well as the negative consequences this incurs to the operational progress, maintenance of equipment in the well and fixed or portable equipment on a rig. This is because the quality of the drilling fluid is influenced by the primary cleaning (filter separator machine with associated filter) through the particle content and size distribution (PSD).